calculate navbar height

caculate_navbar_height.md

• add this javascript

document.documentElement.style.setProperty('--nav-height', document.getElementById("navbar").offsetHeight);

• use property iny css

:root {
    --nav-height: 70px; /*You HAVE To Give A Default Fallback Value*/
}

.container-fs{
    width: 100vw;
    height: calc(100vh - var(--nav-height));
}